7zoom

Ok so I've done a full tune up:
Fuel filter, syn in Trans and diff, Petit cold are intake, air pump removal 3in downpipe with heat wrap, racing beat cat back, TPS adj, new plugs and wires,
coolant flush, new battery and better ground, boost hoses, blow off valve.. the list goes on yet my fuel mileage has not improved at all from the original 16 mpg avg.

I have noticed she runs stronger pulls harder, idles better....

Questions:
1) will letting the car sit for several days ie driven on weekends hurt gas mileage by allowing the fuel to deteriorate or even evaporate?

2) given the same driving conditions should I see better gas mileage with all the basic upgrades and tune up?

3) if some plugs or coils go bad would you be able to notice the difference driving the car?

4) does cooler weather make a difference as in 95 degrees high hum vs. 65 degrees and low humdity?

5) can the petit fuel lubricant clog up the system?

6) what's next new injectors?

p.s. I'm mainly using the gas mileage as an indicator that she is running as well as possible.

Thx
7zoom

catch-22

iTrader: (2)

Did all this tune-up include a new O2 sensor?

Double_J

iTrader: (28)

With the exception of synthetic fluid change, and air pump removal I do not think the other items will improve fuel mileage unless there was a previous issue. Having said that I think the changes you made would have a marginal impact on mileage at best, and likely were erased the first time you stabbed the gas to see if there was a performance difference.

Mahjik

iTrader: (1)

What ECU are you using? Your mileage sounds about right for some mixed highway and street driving.

Six Rotors

iTrader: (17)

There are too many uncontrolled variables in your experiment.I try to test my car's fuel consumption under similar conditions----use the same road,distance,weather etc.Up here in the frozen North,the difference in fuel consumption between summer gasoline and winter gasoline is about 15%(yes more miles with summer gas).
If some of the components you changed were in poor condtion you might expect an improvement in fuel consumption,how much depends.
Anyway if your 16mpg is for mostly stop/go city driving you can expect no more---on a long run few people see better than 23mpg.

7zoom

Yes a new O2 sensor and I'm still running the stock ECU.

I was thinking the reduced exhaust restriction, colder/better flowing intake, reduced resistance "air pump removal aluminum drive pulleys", fresh plugs, wires ect less weight air pump removal lighter battery and exhaust, would all help efficiency/mileage???

I was thinking at least up to 18 average from 16.
I thought the cooler weather alone would help down from 95 down to 65.

Seems like nothing changes my mileage 285 mile to a take no matter what.

I have noticed she smells rich even when fully warmed up. Is that normal with the downpipe and catback set up?



Thx
7zoom

Six Rotors

iTrader: (17)

You use more gas in cooler weather,especially on short runs.If you have a real catalytic converter on the car there should be no smell when the engine is warmed up.

catch-22

iTrader: (2)

welcome to the world of a stock ecu fd

illustrated_FC

iTrader: (1)

Six Rotors : actually you reminded of a question...
my 7 smells a lot like fumes when i warm it up before drive and especially when i let it cool after driving or when im doing city drives.
you think its problem my exhaust or cat that needs to be replaced?


7zoom : im actually trying to solve the same issue with my car eating to much gas. You said you replaced the 02 sensor. maybe it could be our fuel and air ratio is messed up.

is your car stock modified or heavily ?

check also tire air pressure,due to weather change it can contribute to consumption of gas.

maybe your shifting late couple times...?! idk

sounds like you change a good amount of parts to have a decent amount of miles...
-fuel filter
-oil [synthic; how is that oil btw ?]
-air filter
-plugs and wires [important to change]
-i would look into injectors [thats what i been doing maybe the O-rings could be a problem or might need new ones ]
- hows the cat and exhaust on the car ?

let me know how it goes...

illustrated_FC

iTrader: (1)

are they ecu that can have better gas mileage performance...or the set back might be less power?

ericgrau

iTrader: (1)

1) No, as long as you have a gas cap.
2) Assuming the engine has good compression, fixing everything should bring the mpg back up to stock. But not any higher. Replacing the cat should get it slightly higher, but see below.
3) I dunno, but probably depends how bad.
4) This affects power but not mpg assuming all your sensors, etc. are working right.
5) Haven't heard of it, but I doubt it.
6) You'd send your existing injectors to be cleaned if anything. Besides that +1 replace the O2 sensor.

If you make significant upgrades to the exhaust, especially removing the cat, then you need to get some kind of aftermarket fuel control and possibly boost control and then get your car turned conservatively: a little more fuel than necessary to stop detonation. Otherwise you could eventually pop an apex seal. Unfortunately tuning rich also hurts mpg.

Unless something was seriously broken, none of the above should make a huge difference in mpg. There are ways, but they have major drawbacks and would not indicate that the car was in good shape like the OP wanted.

Six Rotors

iTrader: (17)

When you start your RX7 from cold the exhaust will always smell until the engine is fully warmed.Once the engine is warm there should be no smell from the exhaust gases.

Originally they had a warm up catalytic converter in the downpipe which reduced the smell,but most cars now have aftermarket downpipes.

Your smell could be due to a poor cat,no air pump or oil leaking onto the exhaust---

7zoom

Thanks for all the tips. I guess I'm having a hard time understanding how so many "improvements can make the car run so much stronger and have no effect at all on the gas mileage.. I've even noticed I'm putting less pressure on the gas pedal to maintain speed.

She seems more efficent but perhaps not?

I'll check on the cat to see if clogged not sure how, and look into getting the injectors cleaned.

7zoom

Also just to confirm I've been told by Petit I dont need an upgraded ECU with the cold air intake 3 in downpipe and racing beat cat back. I do still have the stock main cat.

They said you only need an ECU upgrad when you start increasing boost.

Agreed Disagree????

Would a power FC make a noticable difference in performance to my set up???

Thx

illustrated_FC

iTrader: (1)

no air pump as in my air pump is probl gone...?

yea went underneath the car the other day and it look pretty rusted down there. If i was to get a down pipe it wont really need that cat but the smell could go away ?

7zoom : yea i will check the cat too. i think ima chk mine over the weekend. How is the racing beat exhuat for your rx7 ?

oppa637

iTrader: (6)

without an airpump on stock ecu will make you run really rich, hence killing your gas mileage

7zoom

I love the Pettit down pipe with heat wrap and racing beat cat back it sounds great and it's not too loud. I prefer not to announce I'm comming from 5 miles away.

Oppa if I understand from my research on this site the air pump only affects the idle up to some low rpm so I dont think it will have much effect on the performance once you get going
at least that why I was okay with removing it and I also like taking that super heavy part off.

The lighter the better IMO

7zoom

catch-22

iTrader: (2)

It will if you get it tuned which will help with the gas milage problem to because you can lean out the cruising areas quite a bit. Also leaning out your boost areas just a tiny bit will also help performance. If you plan on doing any more to the car it would be a wise investment.

spanks13

iTrader: (5)

What does mileage matter if its just a weekend car anyways?

bewtew

iTrader: (7)

16mpg for stop-go driving is not bad.. just try not to be under boost all the time and you should be good .

i get like 8-10 in the city :/

DaveW

I average between 16 and 19 mpg in "local" driving. Local to me usually includes some freeway. The best I have ever gotten was 26 mpg on a long all-freeway trip, mostly at ~70 mph. The worst I have had included a track day - ~10 mpg.

7zoom

I'm only using gas mileage as an indicator of engine tune/performance. I want my car to be tuned to perfection. I'm probably still running a bit rich so I may be getting a power FC unless their is a better option? and then finding someone I can trust to tune.....

On another note I'm wondering if I need to re align my front end now that I've removed significnat weight from the front including the battery, air pump, and stock intake. Could just be me but the gap between the tires and then fender seems to have grown... Suggestions??

bewtew

iTrader: (7)

i think you are over looking at things a little too much

Deals Gap Rotary Rally

iTrader: (6)

In most cases, what you've done wouldn't make much of a difference unless you were having problems before.

Also like others stated, your driving habits will determine what your MPG will be. For instance, my FD I'll get 20+ on highway but soon as I get on, I'll get closer to 12MPG.

I also don't recommend getting a PFC to get better MPG. I always recommend PFC as a tool to monitor some of the vitals of the engine and also to tune to save engines, but not for the purpose of MPG. In your case, PFC will make your car run smoother with the map that came with it but if you are not having any issues, I wouldn't worry about it until you go MP. Which, you would have to worry about boost spikes. Also, FYI: Rotaries like to run rich

You only removed 50lbs... maybe. I don't think that would make any difference that you would need alignment.

Also, if you are running stock springs, it might of sagged during 15+ years. I wouldn't worry about that unless you see signs of abnormal wear on your tires.

Deals Gap Rotary Rally

iTrader: (6)

He is.. But I think it shows his love for these cars. More he knows about it, he'll think differently.

This is the advice I give to those who asked me about what they should get..

PFC as a tool to monitor vitals (water, knock, boost, air temp, etc) more than to tune (this is to start off as a FD owner and later when you learn more, you could then tune on your own. But I wouldn't mess with it until you learn more about tuning).

HKS twinpower to smooth out your ignition. I would get this even if your car is stock. I don't recommend any other ignition systems.

Run all 9 plugs if you boost higher than stock (Just get cheapest NGKs and don't waste your money on platinum and change out often. I change it every other oil change).

Get Aluminum AST.

Change your Oil often! (I change every 2-3 months or 1500-2000miles). I use dino as its cheap. Why spend on synthetic when you change it so often?

Not a fan of premix in the tank if you are streeting your FD.

Hope some of these helps.